HPLC在研究微杆菌D-97胞内酶合成海藻糖机制中的应用

微杆菌D 97胞内酶对麦芽糖的水解微弱 ,并且合成海藻糖的酶反应对磷酸盐无依赖性。采用氨基键合柱HPLC对酶作用的初始底物麦芽寡糖混合物 (Ⅰ )、酶作用 2 4h后未糖化的底物 (Ⅱ )及其糖化水解后的底物 (Ⅲ )分别进行检测对照 ,底物Ⅰ麦芽五糖占34 1 5 % ,底物Ⅱ海藻糖、三糖和五糖分别占 1 7 68%、37 63 %和 3 0 8% ,底物Ⅲ的 2种主要产物葡萄糖和海藻糖各占 77 57%、2 0 2 0 %。通过上述 3种底物二糖至六糖浓度变化的比较 ,发现 DP 值 >4的麦芽寡糖为微杆菌D - 97胞内酶合成海藻糖的较适底物 ,并推断麦芽五糖生成海藻糖的基本方式为 :麦芽五糖→麦芽三糖 +海藻糖。以麦芽五糖为底物的酶反应研究进一步证实了上述作用方式。对于筛选得到的野生菌酶 ,HPLC对照检测从 1个角度为其酶合成海藻糖基本机制研究提供 1种方法。     

磷酸寡糖前体--麦芽低聚糖制备工艺的研究

采用玉米淀粉为原料，以耐高温的α-淀粉酶为液化酶，并以真菌α-淀粉酶为糖化酶制备了以3～6糖为主体的麦芽低聚糖，通过单因素试验确定了液化、糖化的各个工艺参数，得到的最终糖液中麦芽低聚糖含量可高达66％以上。     

Utilization of a Maltotetraose‐Producing Amylase as a Whole Wheat Bread Improver: Dough Rheology and Baking Performance

A maltotetraose‐producing enzyme (G4‐amylase) was utilized to improve the baking performance of whole‐grain wheat flour. Whole‐grain bread dough prepared with G4‐amylase showed reduced water absorption and increased development time, while the dough stability was not affected. Also, the G4‐amylase‐treated samples exhibited lower Mixolab torque values than the control upon heating and cooling. Rheological measurements showed the decreased ratio of R_max/E and increased tan δ, clearly demonstrating that the viscous characteristics of whole‐grain bread dough became dominant with increasing levels of G4‐amylase. The use of G4‐amylase produced whole‐grain wheat breads with a variety of maltooligosaccharides, primarily maltotetraose that positively contributed to the bread volume (1.2‐fold higher than the control). Moreover, G4‐amylase delayed the crumb firming of whole‐grain wheat bread during a 7‐d storage period, showing that it can function as an antiretrogradation agent to enhance the quality attributes of whole‐grain wheat bread.